First, thank you for all your work on both of these SRFIs, and thank you for being so open about the flaws that you now see in them.  All of this will be helpful to anyone else following in your footsteps.  I have spent much of my career working on databases with wildly varying APIs, and I can testify that it's a complicated area.  But it's also super important.

While we can't withdraw the SRFIs without a replacement, I'd be perfectly happy to include a post-finalization note (PFN) in the Status sections of both SRFIs.  If you write a short paragraph summarizing your concerns, I'll put that in the PFN, and then link to your detailed message above — or to another message, if you prefer.  That should ensure that anyone implementing these SRFIs is fully aware of the pitfalls.